This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
In a variety of applications conveyor belts are utilized to move crops, vegetation, and other products. During use such belts repeatedly contact and rub against wheels, pulleys, rollers, and other machinery, as well as stone and organic matter collected from the surrounding environment. As a result of this repeated contact, it is common for belt edges to fray which may cause the belt to unravel. Fraying can be especially pronounced in the case of conveyor belts which become misaligned, unbalanced, or are otherwise unevenly worn.
When belt edges fray, loose strands of belt material become highly susceptible to snagging on machinery and other nearby structures. If loose strands of belt material catch upon such structures while the belt is in use, the strands can be torn from the belt and cause potentially irreparable damage to the belt, machinery, and the products the belt carried.
Problems of fraying and unraveling are inherent in conveyor belts, and especially baler belts. Baler bails are used to manipulate crops in one or more ways. In the context of a round hay baler, multiple belts (usually 4-8 belts) function to take and form incoming rows of crop into a spiral roll of increasing diameter. These belts must withstand incredible amounts of stress from exposure to the elements, such as rain and widely varying temperatures, as well as from stretching to accommodate incoming and large amounts of heavy crops.
U.S. Pat. No. 5,422,165 teaches that baler belts suffer from the heavy loads they are subjected to as they travel around the rollers when baling. The belt edges tend to stretch more than the center of the belt. This is due, at least in part, to an unbalance of load or force dissipation as the load shifts off the center of the belt. This unbalanced load results from the gaps between the belts in the hay baler. When the belts are acting as compressors on the hay bale, the hay tends to bulge out between the gaps resulting in greater stress on the edges of the belt and thus greater elongation. Belts used in agricultural applications and particularly in round, hay balers have inherent problems created by their usual process of manufacture. Moreover, the edges of cut-edge belts and other types of belts tend to curl up against the mechanical guides on the rollers which induces a great amount of stress and flexion at the edges of the belt and, thus, contributes to accelerated fatigue at the edges of the belt. The usual process of belt manufacture involves cutting a large processed sheet of elastomeric into relatively narrow strips which form the core of the belts. The belt disclosed by this patent utilize a wrap of fabric affixed around each longitudinal edge of the belt core. This wrapped belt core is then further processed to create belts with improved longevity and performance characteristics.
U.S. Pat. No. 4,371,580 teaches a three-ply belt having improved dimensional stability, flexing characteristics, and elongation characteristics. In at least one embodiment, a rubber cover is bonded to each outer ply to provide abrasion protection for the belt and to give the machinery on which the belt is used a surface to engage when the belt is in operation.
U.S. Pat. No. 4,900,609 teaches a two-ply belting having improved dimensional stability flexing characteristics and elongation characteristics. Belting in accordance with this invention may be either cut-edge or capped-edge belting. With cut edge belting, the fabrics of the plies are exposed along the edges of the belt. With capped-edge belting, a “cap” of rubber material is bonded to the edges of the belt.
Prior art belts, such as those described above, are not designed to resolve belt edge fraying problems. As a result of their design flaw, glue or covers are typically affixed to the edges of conveyor belts in an effort to slow inevitable edge fraying and the associated damage. Accordingly, there is a need for a conveyor belt which addresses belt edge fraying at its source by being designed to better resist belt edge fraying.